Emulsion containing long chain alkylsulfuric acids



United States 3 Claims. (Cl. 252--312) 'A' non-exclusive, irrevocableroyalty-free license in the invention herein described, throughout theworld for all purposes of the United States Government, with the powerto grant sublicenses for such purposes, is hereby granted to theGovernment of the United States of America.

This application is a division of application bearing Serial No.313,400, filed October 2, 1963, which, in turn, is a division ofapplication bearing Serial No. 21,066, filed April 8, 1960, and now US.Patent No. 3,133,946.

This invention relates to long chain alkylsulfuric acids and to animproved process for the preparation of metal alkyl sulfates as well assalts with nitrogenous bases such as amines and amino acids. The longchain alkylsulfuric acids have now been isolated for the first time aspure compounds with definite melting points. Many of the salts are newcompounds with unusual properties.

The long chain alkylsulfuric acids of our invention have the generalformula ROSO H where R is an n-alkyl group of 12 to 22 carbon atoms; thesalts have the general formulas (ROSO M where when M is a monovalentmetal, an ammonium radical or a substituted ammonium radicalcorresponding to a nitrogenous base 11:1, when M is a divalent metaln=2, and when M is a trivalent metal, then n=3.

An object of our invention is to provide long chain alkylsulfuric acidswhich are surface active agents with unusual properties differingconsiderably from those of the corresponding sodium alkyl sulfates.

The long chain alkylsulfuric acids which we have isolated for the firsttime in a pure state are White crystalline solids with sharp meltingpoints, soluble in aqueous and organic solvents such as ethers, esters,ketones, kerosene, turpentine and paraflinic, aromatic and chlorinatedhydrocarbons. In contrast the sodium alkyl sulfates are insoluble inthese organic solvents and are less soluble in water, particularly inthe case of sodium octadecyl sulfate which has a solubility of only0.02% at 25 C. Although the long chain alkylsulfuric acids are esters ofa strong inorganic acid, we have discovered that 'alkylsulfuric acidssuch as octadecylsulfuric acid are ionized only to the extent of about50% in aqueous solution and appear to exist as incompletely ionizedmicelles with a critical micelle concentration (c.m.c.) only one-thirdof that of sodium octadecyl sulfate.

A further object of our invention is to provide an im proved method forthe preparation of salts of long chain alkylsulfuric acids, in a purestate by a simple process, based upon the isolation of the long chainalkylsulfuric acid.

Sodium salts of long chain alkylsulfuric acids are widely knowndetergents and surface active agents manufactured from the long chainalcohols corresponding to coconut oil or hydrogenated tallow bysulfation with excess of sulfuric acid or other sulfating agent, withsubsequent neutralization of the sulfation mixture by sodium hydroxide.The product contains soduim sulfate and unsulfated long chain alcoholsand further extraction and purification would be required to obtain asubstantially pure sodium alkyl sulfate. Other salts such as thepotassium salt can be prepared in the same way by neutralization of thereatent action mixture but final purification would require additionalsteps.

Neutralization of the entire sulfation mixture as required by the usualmethod is a disadvantage in the preparation of metal alkyl sulfates. Theinorganic base, for example lithium hydroxide or zinc carbonate, must beused in amount sufficient to form the desired metal alkyl sulfate andalso to neutralize the sulfating agent pres ent. Separation of theresulting metal alkyl sulfate from inorganic sulfate, unreacted longchain alcohol and byproducts is difficult and several steps may berequired to isolate a metal alkyl sulfate of adequate purity. Separationdifficulties increase with increase in the molecular weight of the longchain alcohol, particularly when the chain contains as many as l6, 18 or22 carbon atoms.

The method of forming metal alkyl sulfates from a more soluble salt,such as sodium dodecyl sulfate has the disadvantage that it is anindirect method. Furthermore the method of metathesis or doubledecomposition is not feasible for products from alcohols of highermolecular weight since sodium hexadecyl sulfate and sodium octadecylsulfate for example are only sparingly soluble at room temperature;hence it would be difficult and uneconomical to form a less solublemetal alkyl sulfate from the sodium salts.

The disadvantages of the usual methods apparent fo metal alkyl sulfatesexist similarly for salts with amines and amino acids. Briefly,neutralization of the entire sulfation mixture makes separation of puresalts very difiicult, and formation by metathesis, for example from theammonium salt, depends upon adequate difference in solubility betweenthe ammonium salt and the salt to be formed; and frequently this doesnot exist.

In contrast to the usual methods, the method of our invention, whichmakes use of the isolated long chain alkylsulfuric acid, is free fromthe disadvantages recited and leads directly to the formation of saltsof exceptional purity.

The solubility of the long chain alkylsulfuric acids in either water ororganic solvents was found to facilitate the preparation of pure metalalkyl sulfates of mono-, di-, or trivalent metals from the correspondinginorganic bases. such as, for example, lithium hydroxide, magnesiumcarbonate, zinc carbonate, and from the acetates of cadmium, copper,barium, lead, and cobalt, as well as the preparation of pure salts fromammonia, amines, amino acids, or other nitrogenous bases, by suitablechoice of solvents. In most cases the salts are advantageously formed bythe addition of the solid inorganic salt or nitrogenous base to asolution of the long chain alkylsulfuric acid in ethanol or absoluteethanol, followed by filtration at room temperature to obtain the purecrystalline salt of the alkylsulfuric acid. Alternative methods are toadd the metal salt or nitrogenous base as a concentrated aqueoussolution or slurry to a solution of the alkylsulfuric acid in alcohol orwater; or to add the solid metal salt or nitrogenous base to a solutionof alkylsulfuric acid in a solvent such as ether or carbontetrachloride.

According to the present invention long chain alkylsulfuric acids areprepared and isolated in a pure state by a process in which a long chainalcohol, such as an alcohol having 12 to 22 carbon atoms in themolecule, is sulfated at low temperatures, preferably about 30 C. orbelow, by employing a slight excess of a sulfating agent in the presenceof an organic, low-boiling solvent, for example, the halogenatedhydrocarbons which are inert with respect to the sulfating agent toproduce the alkylsulfuric acid, crystallizing the alkylsulfuric acid bycooling the solution to about 0 C. or lower, and rapidly collecting thecrystals from the mixture at low temperature, about 0 C., and in theabsence of moisture to recover pure alkylsulfuric acid.

Rapid filtration, low temprature, and the absence of moisture were foundto be essential to avoid the partial hydrolysis and decomposition whichcan occur in the presence of small amounts of water and concentratedmineral acids during the isolation process.

Rapid filtration and removal of the solid long chain alkylsulfuric acidfrom solvent containing a small amount of mineral acid, in the absenceof moisture, can be accomplished by careful selection of the filteringmedium. A polyethylene filter medium is quite suitable with compressionof the product and exclusion of moisture by means of a rubber dam. Thesame object can be achieved by centrifugation at low temperature,decantation, washing by decantation, and centri-fugation. The productmay then be further dried to remove solvent or may be used directly inthe preparation of salts.

The sulfating agent may be sulfuric acid, oleum, chlorosulfonic acid orother liquid sulfating agent. The halogenated hydrocarbon may bechloroform, carbon tetrachloride, difiuorodichloromethane,tetrachloroethylene, and the like. The preferredv conditions include theuse of chlorosulfonic acid as the sulfating agent, the use of chloroformas the low boiling solvent and the use of higher melting long chainalcohols such as tetradecanol, hexadecanol, octadecanol or docosanol.Commercial mixtures of long chain alcohols such as hydrogenated tallowalcohols and saturated long chain alcohols from marine sources, are alsosuitable starting materials.

Among the amines which may be employed are ammonia, methylamine,ethylamine, ethanolamine, trimethylolmethylamine, 2 amino2-hydroxymethyl-l,3-propanediol, urea, guanidine,Z-benzyl-2-thiopseudourea, aniline, and pyridine.

Among the amino acids which may be employed are glycine, DL-alanine,DL-leucine, L-methionine, DL- aspartic acid, L-glutamic acid,glycylglycine, and betaine.

The long chain alkylsulfuric acids of our invention are surface activeagents and detergents, soluble in water or oil or organic solvents, foruse under acid conditions as textile assistants, emulsifying agents, anddetergents, as in the detergency of wool under acid conditions. The longchain alkylsulfuric acids of our invention are also valuableintermediates for the preparation of metal salts or salts withnitrogenous bases, in an exceptional state of purity. The structure ofthe amino acid salts as substituted ammonium salts derived from theamino group of the amino acid was confirmed by infrared examination.

The long chain alkylsulfuric acids of our invention are also valuableintermediates for the production of ethers, esters and olefins.

The metal alkyl sulfates are detergents and surface active agents,suitable also in lubricant greases, and as addition agents to improvethe properties of lubricating oils.

:TPurity by conversion to the sodium salt ROSOuNa and analysis for so111111.

The purity of the amine and amino acid salts prepared by the process ofour invention is illustrated for salts of octadecylsulfuric acid inTable II.

TABLE II.-AMINE AND AMINO ACID SALTS OF OCTADEC- YLSULFURIC ACIDAnalysis Melting Amine P oglt, Percent N Percent S Found Theory FoundTheory Ammonia 3. 60 3. 81 8. 92 8. 72 Tn'ethylamine 70-72. 5 2. 98 3.10 6. 90 7. 09 Triethanolamine. 86. 0-86. 8 2. 78 2. 6. 56 6. 42 2amino2-hydroxymethyl-1,3-p1'opanediol 124-127 2. 94 2. 97 6. 72 6. 79Urea 113-114 6. 68 6. 82 7. 75 7. 81 Guanidine 145-146. 4 10. 26 10. 267. 67 7. 83 2-benzyl-2-thiopseudourea 95. 897. 2 5. 45 5. 40 11. 7212.41 Aniline 124. 8-125. 8 2. 79 3. 16 7. 87 7. 23 Pyridine 103-106. 53.17 3. 26 7. 75 7. 46

AMINO non) 3. 33 3.29 7. 01 7. 53 3. l9 3. 26 7. 29 7. 38 3.14 2. 91 6.78 6. (i6 2. 78 2.80 12. 97 12.83 D L-aspartic aeid 2. 89 2. 89 6. 636.90 L-glntamic acid 18-83 2. 64 2. 82 6. 01 6. 44 Glycylglycine 1 5. 615. 81 6. 60 6. 64 etaine 108109 2. 94 3. 00 6. 83 6. 85

1 Amino acid salts in general do not have definite melting points.

The purity of metal alkyl sulfates prepared by the process of ourinvention is illustrated for salt-s of octadecylsulfuric acid in TableIII.

TABLE III.METAL SALII LSCI%F OOTADECYLSULFURIC Analysis Melting Point,Metal Ion 0. Percent Metal Percent S Found Theory Found Theory 1. 93 1.95 9. 04 8.99 6.15 6. l7 8. 58 8. 61 10 11 I0. 06 8. l7 8. 25 7 23 7.01

1. 35 1. 27 3. 37 3. 36 5. 40 5. 42 ll. l8 11. 14 16. 30 16. 42 7. 76 7.78 8. l4 8. 33 8. 59 8. 56 13. 77 13. 85 22. 22. 86 2. 36 2. 54

lvietal alkyl sulfates in general do not have sharp definite, meltingEXAMPLE I Octadecylsulfuric acid n-Octadecanol, 0.4 mole, 108 g., 111.4359, M.P. 58.l58.6 C., was added to 540 ml. of chloroform (5 ml./ g.solvent ratio) in a 2-liter, 3-neck flask equipped with a mechanicalstirrer, a thermometer, and a graduated, side-arm type, addition tube.The mixture was warmed to 30 C. to complete solution, cooled to ice bathtemperature (45 C.) and 0.432 mole (50.4 g., 8% excess) ofchlorosulfonic acid Was added dropwise with stirring during 18 minutesof 47 C. Stirring was continued for three hours at 1530 C. and thesolution was allowed to crystallize overnight at 0 C.

To maintain low humidity conditions and insure rapid filtration atreduced pressure the crystalline solid-solvent mixture was filteredthrough a polyethylene filter medium on a Biichner funnel in a lowhumidity room at 0 C. A layer of vinyl sheeting was placed on top of thecrystalline mass in the funnel and then a rubber dam to excludemoisture, compress the crystalline mass, and hasten filtration. Thepolyethylene filter was necessary because filter paper becomesparchmentized by the sulfating agent. The vinyl sheeting protected thecrystalline solid from contamination and stain by the rubber dam.

Octadecylsulfuric acid was obtained as a white crystalline solid, M.P.5152, yield 66%, with the analysis shown in Table I. Further quantitiesof less pure octadecylsulfuric acid could be obtained from thechloroform filtrate.

EXAMPLE II Hexadecylsulfuric acid n-I-Iexadecanol, 0.2 mole, 48.7 g., 111.4359, M.P. 49.349.6, was added to 146 ml. of chloroform (3 ml./g.solvent ratio) in a 1-liter, 3-neck, flask equipped with a mechanicalstirrer, a thermometer, and a side arm type addition tube. The mixturewas warmed slightly to complete solution, cooled to 4 C., and 0.216 mole(25.2 g., 8% excess) of chlorosulfonic acid was added dropwise during 12minutes at 3-7 C. Stirring was continued for one hour at 15-30 C. andthe solution was allowed to crystallize overnight at 0 C.

The crystalline solid-solvent mixture was filtered at 0 C. under lowhumidity conditions as described in Example I. Hexadecylsul'furic acidwas obtained as a white crystalline solid, M.P. 40-42, yield 63%, withthe analysis shown in Table I. Analyses for C and H gave 59.51% C,10.71% H, in good agreement with the theoretical values of 59.59% C and10.63% H.

EXAMPLE III Tetradecylsulfuric acid n-Tetradecanol, 11 1.4318, M.P.37.238.0, was sulfated with chlorosulfonic acid under the conditions ofEX- ample I, but with a lower solvent ratio (2.5 ml. of chloroform/ g.of tetradecanol).

Tetradecylsulfuric acid was isolated under low humidity conditions as aWhite crystalline solid, M.P. 37-39", yield 75%, with the analysis shownin Table I.

EXAMPLE IV Dodecylsulfuric acid n-Dodecanol, 11 1.4410, M.P. 24.1 C.,was sulfated with chlorosulfonic acid under the conditions of Example Ibut with a lower solvent ratio (2.5 ml. of chloroform/ g. of dodecanol).

Dodecylsulfuric acid was isolated by crystallization at 20 C. andfiltration at 0 C. under low humidity conditions, as a white crystallinesolid, M.P. 25-27 C. with the analysis shown in Table I.

EXAMPLE V Ammonium octadecyl sulfate Concentrated aqueous ammonia, 2.5ml., 29% was added dropwise to a stirred solution of g. (0.0285 mole) ofoctadecylsulfuric acid in 50 ml. of absolute ethanol at 10-15 Themixture was heated to the boiling point, the hot turbid solution wasfiltered, and the clean filtrate was allowed to crystallize at roomtemperature.

Ammonium octadecylsulfate, CI3H37OSO3NH4, was obtained as a whitecrystalline solid, neutralization equivalent 365 (theory 368), yield80%, with the analysis shown in Table II.

EXAMPLE VI Triethlylammonium octadecyl sulfate Triethylamine, 4.8 g.,was added in portions to a solution of 10 g. of octadecylsulfuric acidin 40 ml. of carbon 6 tetrachloride at 1520 and the clear solution wasallowed to crystallize at 0 C.

Triethylammonium octadecyl sulfate,

Was obtained as a White crystalline solid, M.P. 70-72.5 C.,neutralization equivalent 453 (theory 452), yield 66%, with the analysisshown in Table II.

EXAMPLE VII Triethanolammonium ocladecyl sulfate Triethanolamine, 6.6g., was added dropwise to a slurry of 15 g. (0.0427 mole) ofoctadecylsulfuric acid in 160 ml. of carbon tetrachloride at 1015 C. Themixture was heated to the boiling point, filtered hot, and the filtratewas allowed to crystallize at room temperature.

The salt was obtained as a slightly yellow product, neutralizationequivalent 488 (theory 500), yield 93%; recrystallization from methanolgave triethanolammonium octadecyl sulfate, C H OSO NH(C H OI-I) M.P. 86-86.8 C., neutralization equivalent 500, yield 73%, with the analysisshown in Table II.

EXAMPLE VIII Urea salt of octadecylsulfuric acid Urea, 1.71 g., wasadded in portions to a solution of 10 of octadecylsulfuric acid in 55ml. of absolute ethanol at 23-29" C. Stirring was continued for 1.5hours and the mixture was filtered at room temperature.

The urea salt, CmHyOSOgNHgCONHg, was obtained as a white crystallinesolid, M.P. 113-114" C., neutralization equivalent 412 (theory 411),yield 64%, with the analysis shown in Table II.

EXAMPLE IX Guanidine salt of octadecylsulfuric acid Guanidine carbonate,2.57 g., was added to a solution of 10 g. of octadecylsulfuric acid inml. of 95% ethanol at 2325 C. The mixture was stirred for three hoursand allowed to crystallize at 0 C.

The guanidine salt was obtained as soft white crystals, M.P. -146.4 C.,yield 87%, with the analysis shown in Table II. Since guanidine is astrong base the guanidine salt of octadecylsulfuric acid is neutral.

EXAMPLE X Aniline salt of octadecylsulfuric acid Aniline, 2.65 g., wasadded dropwise to a solution of 10 g. of octadecylsulfuric acid in 50ml. of absolute ethanol at 7 C. Heat of neutralization raised thetemperature to 19 C. Stirring was continued for ten minutes and themixture was filtered at room temperature.

The aniline salt C H OSO NH C I-I was obtained as white crystallineplatelets, M.P. 124.8125.8 C., neutralization equivalent 444 (theory444), yield 86%, with the analysis shown in Table II.

EXAMPLE XI Pyridine salt of octaclecylsulfuric acid Pyridine, 2.75 g.,was added dropwise to a solution of 10 g. of octadecylsulfuric acid in75 ml. of absolute ethanol at 1217 C. Stirring was continued for onehour and the mixture was filtered at room temperature.

The pyridine salt, C H OSO NHC H was obtained as a white crystallinesolid, M.P. 103l06.5 C., neutralization equivalent 433 (theory 430)yield 86%, with the anlysis shown in Table II.

EXAMPLE XII Glycine salt of octadecylsulfuric acid Glycine, 2.6 g., wasadded to a stirred solution of 10 g. of octadecylsulfuric acid in 90%ethanol at 25 C. The mixture was heated to 60 C. then cooled to 30 C.,filtered to remove a small excess of glycine and allowed to crystallizeat room temperature.

The glycine salt, C H OSO NH CH CO H, was obtained as a white solid,yield 80% with the analysis shown in Table II.

EXAMPLE XIII DL-leucine salt of octadecylsulfuric acid 'DL-leucine, 2.2g., was added in portions to a solution of 10 g. of octadecylsulfuricacid in 100 ml. of absolute ethanol at 25 C. The mixture was heated to60 C., cooled to 40 C., filtered to remove a small excess of leucine andallowed to crystallize at C.

The DL-leucine salt was obtained as a white solid, yield 56%, with theanalysis shown in Table II. Infrared examination confirmed that the saltmay be represented as since the CO H is present wit-h no ionization tothere is no free amine, the band for NH could be detested andcharacteristic absorption for sulfate ester was also present.

EXAMPLE XIV Betaine salt of octadecylsulfuric acid Betaine monohydrate,3.86 g., was added to a solution of 10 g. of octadecylsulfuric acid in100 ml. of absolute ethanol at 2230 C. Stirring was continued for 1.5hours and the mixture was filtered at room temperature andrecrystallized from absolute ethanol.

The beta-1 116 Salt, C18H3'7OSO3N(CH3)3CH2CO2H, Was obtained as softwhite crystals, M.P. l08-l09 C, neutralization equivalent 466 (theory468), yield 64%, with the analysis shown in Table II.

EXAMPLE XV Lithium salt of octa ecylsulfuric acid Lithium hydroxidesolution, 15 ml., aqueous, was added stepwise to a solution of g. ofoctadecylsulfuric acid in 50 ml. of absolute ethanol at 10-15 C. Themixture was stirred for about 1 hour at room temperature then allowed tocrystallize at 0 C. overnight.

The white product, yield 85%, recrystallized from absolute ethanol gavelithium octadecylsulfate, C H OSO Li, M.P. l84.5185.5, d., yield 67%,with the analysis shown in Table III.

EXAMPLE XVI Magnesium salt of octadecylsulfuric acid Magnesiumcarbonate, 4MgCO -Mg(OH) -nH O, 1.4 g., was added in portions to asolution of 10 g. of octadecylsulfuric acid in 100 ml. of 95% ethanol at10-15 C. On stirring for 5 minutes at room temperature a thick pasteresulted. The mixture was heated to the boiling point, filtered hot, andthe filtrate allowed to crystallize at 0 C.

The white, crystalline product (C H OSO Mg, yield 68%, M.P. 200, gavethe analysis shown in Table III.

8 EXAMPLE XVII Cadmium salt of octadecylsulfuric acid Cadmium acetate,3.8 g., was added in portions to a solution of 10 g. ofoctadecylsulfuric acid in 50 m1. of ethanol at room temperature (20 C.).The mixture was stirred for one hour, heated to the boiling point on thesteam bath, then filtered hot and the clear filtrate was allowed tocrystallize at 0 C.

The white crystalline salt recrystallized from absolute ethanol gavecadmium octadecyl sulfate M.P. 193-196", d., yield 72% with the analysisshown in Table III.

EXAMPLE X VIII Copper salt of octadecylsulfuric acid Cupric acetate, 2.8g., was added in portions to a solution of 10 g. of octadecylsulfuricacid in 50 ml. of 95 ethanol at room temperature. After stirring for 30minutes the pasty mixture was heated to the boiling point on the steambath, filtered hot, and the clear filtrate allowed to crystallize atroom temperature. The blue-green cupric octadecyl sulfate,(C13H37OSO3)2CU, yield 80%, M.P. -l40, d., gave the analysis shown inTable III.

EXAMPLE XIX Barium salt of octadecylsulfuric acid Barium acetatemonohydrate, 3.9 g. in 5 ml. of distilled water, was added stepwise toasolution of 10 g. of octadecylsulfuric acid in 100 ml. of absoluteethanol at room temperature. The temperature rose to 30; stirring wascontinued for 10 minutes. The white precipitate obtained on filtrationwas then heated in 400 ml. of 50% ethanol solution and filtered hot.White barium octadecyl sulfate, (C H OSO Ba, yield 90%, M.P. 172.8173,d., gave the analysis shown in Table III.

EXAMPLE XX Lead salt of octadecylsulfuric acid Cobalt salt ofoctadecylsulfuric acid Cobalt acetate, 3.6 g. in 10 ml. of distilledwater, was added stepwise to 10 g. of octadecylsulfuric acid in 50 ml.of absolute ethanol at room temperature. After 20 minutes stirring thepasty mixture was heated to boiling, filtered and the clear filtrateallowed to crystallize at 0 C.

The pink crystalline solid (cobaltous oxide ash 10.2%, theory 9.9%)yield 89%, on recrystallization from absolute ethanol gave cobaltoctadecyl sulfate,

yield 78%, M.P. d., with the analysis shown in Table III.

EXAMPLE XXII Zinc salt of octadecylsulfuric acid Zinc carbonate, 1.8 g.,was added in portions to 10 g. of octadecylsulfuric acid in 55 ml. ofabsolute ethanol at room temperature. The mixture was stirred for 30minutes, heated to the boiling point on the steam bath, filtered hot andthe clear filtrate allowed to crystallize at C.

The white powdery zinc octadecyl sulfate,

yield 89%, MP. indefinite about 150, d., gave the analysis shown inTable III.

EXAMPLE XXIII Aluminum salt 0 octadecylsalfuric acid Al (SO -l8H O, 4.1g. in 10 ml. of distilled water, Was added to 10 g. of octadecylsulfuricacid in 800 ml. of distilled water at 60 C.; the mixture was stirred for20 minutes, filtered hot and the sticky white material taken up in 25ml.of'absolute ethanol and allowed to crystallize at0 C.

White amorphous hygroscopic aluminum octadecyl sulfate, (C H 7OSO Al,yield 89%, MP. 153162, d., gave the analysis shown in Table III.

Properties of long chain alkylsalfuric acids, salts with amino acids,and long chain metal alkyl sulfates Octadecylsulfuric acid, as anexample of the long chain alkylsulfuric acids of our invention was foundto have a surprisingly low critical micelle concentration, aboutonethird of the value for sodium octadecyl sulfate. The c.m.c. by thedye titration method was found to be 0.0387 millimoles/l. Conductanceand pH measurements of aqueous solutions of octadecylsulfuric acidincluding measurements at both above and below the c.m.c. indicate thatoctadecylsulfuric acid is about 50% ionized over a considerableconcentration range, indicating that in aqueous solutionsoctadecylsulfuric acid exists as a micelle composed of ionized andun-ionized molecules.

Octadecylsulfuric acid was found to be surprisingly resistant tohydrolysis. Hydrolysis of a 0.05 molar solution at 100 C. was 50% inless than half an hour, about equal to that for sodium octadecyl sulfateacidified with an equivalent amount of mineral acid. However, at 60 C.140 F.), a frequently selected washing temperature, the degree ofhydrolysis was only 10% after 3 hours and 16% after 7 hours. Thesekinetic data do not fit conventional rate expressions becausemicellization occurs with a decrease in the concentration of simple ionsand molecules. The surprising degree of stability of the long chainalkylsulfuric acids to hydrolysis increases their general field ofusefulness. Other properties of octadecylsulfuric acid, and of the amineand amino acid salts are illustrated in Table IV.

The data of Table IV demonstrates a useful degree of solubility for thelong chain alkylsulfuric acid and its salts in both water and organicsolvents. The data also demonstrates detergent and surface activeproperties. The low interfacial tension of the amino acid saltsindicates exceptional emulsifying properties, further evident in TablesV and VI. The best detergents for cotton of those evaluated in Table IV,are the octadecylsulfuric acid, the salt with2-amino-2-1ydroxymethyl-1,3-propanediol, and the glycine salt, whichremove soil from cotton under acid conditions without damage to thefiber. Similar evaluation with standard soiled wool showed thatoctadecylsulfuric acid was a better detergent at 45 C. than a wellestablished commercial detergent (sodium dodecyl sulfate) and arepresentative ester type nonionic detergent (oxyethylated oleic acid.)

The long chain alkylsulfuric acids of our inventionan'd the amine andamino acid salts thereof are excellent emulsifying agents quite supeniorto sodium oleate and commercial surface active agents, as shown inTables V and VI. The salts of the long chain alkylsulfuric acids havethe further advantage that they may be formed in situ from a solution ofthe long chain alkyl sulfuric acid in the organic solvent or oil phaseand an aqueous solution of the amine or amino acid. Conversely the saltsmay be formed in situ from an aqueous solution of the long chainalkylsulfuric acid and a solution of the amine or amino acid in anorganic solvent. In situ formation of the emulsifying agent at theinterface or junction of the two immiscible liquids is often veryeffective in the formation of stable technical emulsions.

TAB LE V.-E1\IULSIFYIN G PROPE RTIES 1 Briggs, 'I. R., J. Phys. Chem.24, 120-126 (1920); time required for 10 ml. to break from an emulsionof 40 ml. paraffin oil with 40 ml. 0.1% solution of emulsifying agent indistilled water.

TABLE IV.PROPERTIES OF OCTADECYLSULFURIC ACID, AMINE SALTS AND AMINOACID SALTS Solubility (25 0.), Percent 0.1% Aqueous Solutions Surfaceand Inter- Acid or Salt pH facial Tension, dynes/ Detergency 1 at C.Foam cm. Height 2 Water Butanol Chloroform 00 C.

S.T. LT. Cloth A Cloth 13 Oetadecylsulfuric Acid 1 5 10 3. 13 41. 6 10.4 40. 2 23. 4 195 Amine Salts:

Triethylamine. 1 10 10 5.15 38. 4 7. 0 13. 8 12. 4 190 Triethanolamine10 1 0. 1 5.15 40. 9 7. 0 19. 0 19. 8 190 2-amino2-h 'dro.1,3-propariediol- 1 0. 1 0.1 4.90 40.1 9.1 29 4 21.9 20;: A n Ac'dSalts:

Gfycin e 0. 1 0. 1 0. 1 3. 40 41. 1 6. 5 39. 7 22. 9 210 DL-Leucine 0. 55 5 3. 3O 36. 1 4. 3 9. 9 16. 6 L-Methionine 1 10 5 3. 30 37. 4 5. 9 13.4 18. 4 200 1 Mr starred as increase in reflectance after washing in theTerg-OTometer.

ng cotton.

' Ross-Miles pour foam test (0118: Soap 18, 99-102 (1941)).

Cloth A and Cloth B represent different soil removal problems in wash-TAB LE VI.EMULSIFYIN G PROPE RIIES Relative Stability of Emulsion withImmiscible Organic Solvents. Method of Atlab Emulsion Testing ApparatusEmulsifying Agent Organic Solvent Time Salts of octadecylsulfuric acid:

nonionic surface active agents.

W. C. Griffin and R. W. Behrens, Anal. Chem. 24, 10767 (1952). Emulsionsprepared by mechanically shaking 25 ml. organic solvent with 25 ml. 0.2%solution of emulsifying agent in water; noting the time required for 10%separation from the emulsion.

2 Salt prepared in situ from an aqueous solution of the amine or aminoacid and a solution of octadecylsuliurie acid in the organic solvent.

The solubility of the pure metal alkyl sulfates prepared by the processof our invention is illustrated in Table VII in the case of saltsderived from the isolated octadecylsulfuric acid.

Most of the metal alkyl sulfates of Table VII are insoluble or nearly soin Water, benzene, carbon tetrachloride and Skellysolve B. The ammonium,silver, beryllium, cobalt, copper and aluminum salts have surprisingsolubilities of 5% or greater in one or more of the representativeorganic solvents. Salts capable of forming an ammonio complex,particularly the silver and copper salts, are quite soluble in aniline.Many of the metal salts are soluble to the extent of 1% or greater inplasticizers and lubricants and remain in solution even at C, Thelithium, potassium, silver, beryllium, magnesium, strontium, zinc,cadmium and lead salts are soluble to a surprising degree in trioctylphosphate. The lithium, potassium, beryllium, strontium and lead saltsare soluble in many plasticizers and lubricants. Solubility inlubricants indicates usefulness as an addition agent to improve theproperties of lubricating oils.

TABLE VIL-SOLUBILITY OF PURE METAL ALKYL SULFATES OF OCTADECYLSULFURICACID, AT 25 C.

Metal Ion Water,

percent Butanol, percent Aniline, percent DOP, DOS, TOP. DBS, SAE-IO,TOP. TOP

DB8, DOP, DOS,

SAE-10, TOP. TOP.

Solubility of 1% or greater. DBS dibutyl sebacate, DOP dioctylphthalate, DOS dioctyl sebaeate, SAE-IO petroleum lubricating oil, TOPtrioctyl phosphate.

2 The symbol i indicates a solubility of less than 0.1%.

We claim:

1. An emulsion consisting essentially of a liquid halogenatedhydrocarbon, water, and about from 0.05% to 0.1% of the DL-leucine saltof octadecylsulfuric acid as the emulsifying agent therefor.

2. The emulsion of claim 1 wherein the halogenated hydrocarbon isselected from the group consisting of cholorform, carbon tetrachloride,tetracholoroethylene, and o-dichlorbenzezne.

3. The emulsion of claim 1 wherein the halogenated hydrocarbon and waterare present in the ratio of about 1:1 by volume.

References Cited by the Examiner UNITED STATES PATENTS 1,917,252 7/1933Harris 2523l2 2,447,475 8/1948 Kaberg et al. 252-3 12 XR 2,525,07810/1950 Pabst et al. 252l53 XR 2,781,392 2/1957 Mannheimer 260-459FOREIGN PATENTS 440,576 1/1936 Great Britain. 492,742 9/ 1938 GreatBritain.

OTHER REFERENCES Uchiumi et al.: Chemical Abstracts, 52 (1958), p. 8185.

LEON D. ROSDOL, Primary Examiner. ALBERT T. MEYERS, Examiner.

S. E. DARDEN, Assistant Examiner.

1. AN EMULSION CONSISTING ESSENTIALLY OF A LIQUID HALOGENATED HYDROCARBON, WATER AND ABOUT FROM 0.05% TO 0.1% OF THE DL-LEUCINE SALT OF OCTADECYLSULFURIC ACID AS THE EMULSIFYING AGENT THEREFOR. 